Most students in the U.S. have used or at least heard of Quizlet, the website for creating digital flashcards.

The company leverages machine learning to predict in which areas its users need the most help and provides 300 million user-generated study decks, maps, charts and other tools for learning.

Roughly eight months after closing a $20 million financing, Quizlet chief executive officer Matthew Glotzbach has disclosed some notable feats for the emerging edtech: it’s reached 50 million monthly active users, up from 30 million one year ago, and though it’s not profitable yet, its revenue is growing 100 percent YoY.

As a result of its recent growth, the company is opening its first office outside of Silicon Valley, in Denver.

“We by no means feel like our work is done; 50 million is a very small fraction of the 1.4 billion students on the planet,” Glotzbach told TechCrunch. “Our focus is growing the platform. If we continue to be successful in that mission, we will be the largest study and learning brand.”

The company has been around for a while. Founded in 2005 by then 15-year-old Andrew Sutherland, Quizlet was fully bootstrapped until 2015.

Its growth really began when Glotzbach, a seasoned executive most recently at YouTube, took the reigns in 2016. The $20 million round earlier this year, its largest yet, has allowed the company to blossom, too. Led by Icon Ventures, with participation from Union Square Ventures, Costanoa Ventures and others, it brought Quizlet’s total raised to just over $30 million.

Part of its growth, according to Glotzbach, has to do with its recent focus on its international users. The site has always been accessible around the world, but not until late 2016 did Quizlet begin offering the tool in other languages. Today, it’s available in more than 15 languages, a number the company is actively working to expand.

Newly added capabilities have also contributed to recent spikes in MAUs. Students can now access diagram-based content, which is helpful for STEM subjects, an area the company has historically been less helpful with.

Quizlet operates a freemium model but has three subscription products for power users. At $12 per year, Quizlet Go has no ads and provides an offline studying option on mobile. Quizlet Plus, at $20 per year, also provides an ad-free study experience, as well as image uploading and voice recording capabilities. Finally, Quizlet for Teachers offers educators a $35 per year option that lets them create their own decks for students and access to additional data, analytics and reporting.